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The work function for zinc is 4.31 $\mathrm{eV}$ (a) Find the cutoff wavelength for zinc. (b) What is the lowest frequency of light incident on zinc that releases photoelectrons from its surface? (c) If photons of energy 5.50 $\mathrm{eV}$ are incident on zinc, what is the maximum kinetic energy of the ejected photoelectrons?

a. 5.41 \times 10^{14} \mathrm{Hz}

b. 1.04 \times 10^{15} H z

c. 1.19 e V

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Rutgers, The State University of New Jersey

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McMaster University

case on this problem. We're talking about zinc, and we're told that the work function is 4.31 you be, and we want caught off wavelength. So caught off way blink is gonna be when electrons were omitted, But they have no kinetic energy. So in the usual formula for the photoelectric effect, which is kinetic energy is the energy of the photon minus the work function. Um, we can say that this is zero. So that we can say is he called a bye. And then whatever you solving for again, um, Lois frequency and then we want to use is equal to h f. So f is equal to fi over age. So if we do 4.31 designed by needs, then we need to convert the 4.31 to drools by multiplying by 1.602 times 10 to the minus 19. Um, And then with that, I got one point. 04 times 10 to the 15 hurts. And so that's the answer for hopes we wanted to find the wavelength for us. Well, that's OK. On the frequency first, and then you for a We want to use frequency is equal to see over Lambda and then land us, therefore equal to see over after. And so what we want to do is take the inverse of our frequency and multiply it by the speed of light. So I'll do this minus one times the speed of light. And I got 2.88 um, 288 nanometers. And for see, um, we know the energy of the photons. We want the Max Kinetic energy. So, um, again, we can use this formula, but without the without, the key crossed out. So, for a C, you're gonna say kinetic energy, um, is just the energy of the foe times. And then that's what they give us. Um, 5.5 u v minus 4.31 Okay, so then this is 0.69 plus 0.5 is, um, 0.69 plus 0.5 is one 0.19 Does that work out groups Not one equals 0.19 gov. So, yeah, they've they've been ejected. You've had to kind of spend this much on the work function just to take them out of the the electrons out of the structure. And, um, and then you have this much left over which is converted into Connecticut, and she

University of Washington